Fire retardants are well-known and are typically added to and/or applied as a surface treatment to help prevent the spread of fire and/or protect a material exposed to fire. Commercially available fire retardants may be obtained in great variety, including examples such as bromine-based fire retardants, phosphorous-based fire retardants (e.g., ammonium polyphosphate (APP)), nitrogen-based fire retardants (e.g., melamine), inorganic-based fire retardants, and chlorine-based fire retardants.
A fire retardant can also be classified by the mechanism in which it acts as a fire retardant. A well-known flame retarding mechanism is known as “intumescence,” and is attributable to the fire retardant category known as “intumescents.” Intumescent fire retardants expand and form a char layer as a barrier between the underlying material and surrounding environment. This char layer is hard to burn, and insulates and protects the underlining material from burning. Intumescents operate by expansion either as a result of a chemical reaction under heat, or as by a primarily physical reaction that occurs due to the configuration of components in the intumescent material. Examples of chemical intumescents include phosphate-based materials and silica gel/potassium carbonate mixtures. Examples of physical intumescents include expandable graphite.
Fire retardants can be used with a wide variety of items such as furniture, floors (e.g., floor coverings), decks (e.g., deck coverings), textiles, cables, building materials and insulation, electrical equipment, structures like pipe racks, equipment foundation, supporting structures, columns, beams, transportation equipment (e.g., truck-bed liners), roofs (e.g., roof coating), and the like. It would be desirable to use fire retardants in two-part, isocyanate-base, curable systems to provide cured compositions with flame retardancy, but often such use is not a reality because of technical hurdles involved in incorporating fire retardants in two-part, curable systems.
There is a continuing need for new and improved fire retardant systems that can be readily applied to surfaces and in particular, to existing building structures.